column-alteration:

1 column-name
2+ 
2 SET
2.1? DATA TYPE data-type
2.2+ 
2.2.0.0 default-clause
2.2.0.0! GENERATED ALWAYS
2.2.0.0?
2.2.0.0 GENERATED BY DEFAULT
2.2.0.1 (1) 

2.2.0 NOT NULL
2.3 (2) 

2 DROP
2.1+ 
2.1.0 DEFAULT
2.1.0 NOT NULL
2.1.0 IDENTITY
2.2 (2) 

2 identity-alteration

identity-alteration:

1+ 
1 SET
1.1 INCREMENT BY numeric-constant
1.1 NO MINVALUE
1.1 MINVALUE numeric-constant
1.1 NO MAXVALUE
1.1 MAXVALUE numeric-constant
1.1 NO CYCLE
1.1 CYCLE
1.1 NO CACHE
1.1 CACHE integer
1.1 NO ORDER
1.1 ORDER
1 RESTART
1.1? WITH numeric-constant
1.2 (2)